afiŝo

A poster: a sheet printed with an announcement and stuck somewhere public. Concert bills, election posters, the notice on a shop door. The verb afiŝi is to post one up, afiŝtabulo is a noticeboard, and the person who does the sticking is an afiŝisto.

Say it with joy: afiŝo is not a plus fiŝo. There is no article a in Esperanto, fiŝo is a fish, and a poster is not a fish. This is the seam that looks most inviting in the whole chapter and it is entirely imaginary. Afiŝ- is one borrowed root from French affiche, and the resemblance to a fish with something in front of it is a coincidence of spelling and nothing more. If a learner ever tells you a bill posted on a wall is somehow a fish, you now know where they went wrong.

One modern extension worth having. Since the mailing-list era, afiŝi has also meant to post a message to a forum or a list, and an afiŝo can be that message. The logic is exactly English's: something pinned up in public for anyone to read, as opposed to a letter sent to one person. So mi afiŝis en la grupo means you posted in the group, and nobody will picture glue.